Green M H, O'Neill J P, Cole J
MRC Cell Mutation Unit, Sussex University, Falmer, Brighton, UK.
Mutat Res. 1995 Jun;334(3):323-39. doi: 10.1016/0165-1161(95)90070-5.
Mutant frequency is defined as the proportion of mutant cells in a population and is readily estimated. It should be distinguished from mutation rate, which relates to the rate at which mutation events arise, and is generally expressed as events per cell division. Since one mutation event may give rise to one or many mutant cells, depending on the generation in which it has arisen, the relationship of mutant frequency to the underlying mutation rate is complex. A large number of estimates of mutant frequency at the hprt locus in human lymphocytes are available, from our two laboratories among others. From our two extensive data sets, we have determined median hprt mutant frequencies of different age groups and used the method of Lea and Coulson (J. Genet., 49, 1949, 264-285) to attempt to estimate the underlying mutation rate at this locus. It is in principle possible to obtain estimates of mutation rate from the mutant frequency in newborns, from the increase in mutant frequency with age, and from the difference between the upper and lower quartile mutant frequencies. We discuss reasons for the discrepancies between these estimates and argue that the best estimate can probably be obtained from the increase in mutant frequency with age. We arrive at an estimate of mutation rate to 6-thioguanine resistance at the hprt locus of about 5 x 10(-7) mutation events per nominal cell division.
突变频率定义为群体中突变细胞的比例，并且易于估算。它应与突变率区分开来，突变率与突变事件发生的速率相关，通常表示为每细胞分裂的事件数。由于一个突变事件可能产生一个或多个突变细胞，这取决于它发生的代数，所以突变频率与潜在突变率之间的关系很复杂。在人类淋巴细胞的次黄嘌呤 - 鸟嘌呤磷酸核糖转移酶（hprt）位点，有大量来自包括我们两个实验室在内的多个实验室的突变频率估算数据。从我们两个广泛的数据集，我们确定了不同年龄组的hprt突变频率中位数，并使用Lea和Coulson的方法（《遗传学杂志》，第49卷，1949年，第264 - 285页）试图估算该位点的潜在突变率。原则上，可以从新生儿的突变频率、突变频率随年龄的增加以及上下四分位数突变频率之间的差异来获得突变率的估算值。我们讨论了这些估算值之间存在差异的原因，并认为最好的估算值可能来自突变频率随年龄的增加。我们得出在hprt位点对6 - 硫鸟嘌呤抗性的突变率估计约为每名义细胞分裂5×10⁻⁷个突变事件。
